1. Field of the Invention
The present invention relates to a device for stimulating living tissue, of the type having a stimulation unit which emits stimulation pulses from a pulse signal output socket, an electrode system which delivers the stimulation pulses to the living tissue, a controllable switching device connected between the electrode system and the pulse signal output socket for transmitting the stimulation pulses to a specific part of the electrode system, and a control device which emits control signals from a control output socket to a control input socket on the switching device to control the transmission of stimulation pulses.
2. Description of the Prior Art
A device of the type generally described above is disclosed in U.S. Pat. No. 4,628,934. This known device contains a pacemaker, a switching unit and an electrode system. The electrode system consists of two multipolar electrodes which can be unipolarly or bipolarly connected to the pacemaker via the switching unit. The switching unit is controllable, and is directly controlled from pacemaker electronic circuitry via control lines.
By means of the switching unit, the required number of feedthroughs to pacemaker electronic circuitry, which is enclosed in a pacemaker case, can be reduced. In a unipolar version, one feedthrough is employed for delivering stimulation pulses from pacemaker electronic circuitry and control lines for controlling the switching unit. In a bipolar version, there are two feedthroughs, each with a line for delivering stimulation pulses, and control lines to the switching unit. In one version of this known device, a serial-to-parallel signal converter is employed in the switching unit to reduce to one the number of control lines to the pacemaker electronic circuitry. A pulse train, which in the serial-to-parallel signal converter is applied in parallel to the switches in the switching unit, is then fed through this single control line. When the switching device is devised in the form of a detachable adapter for a pacemaker, two electrodes can be coupled, via the adapter, to a pacemaker designed for one electrode.